SAGA complex

Definition

Target type: cellularcomponent

A SAGA-type histone acetyltransferase complex that deubiquitinates H2A and/or H2B. This complex is organized into several functional submodules: a structural core including the activator binding module and consisting of ADA1 or a homolog, members of the SPT and TAF protein families as well as promotor recruitment factor TRRAP/TRA1, a histone acetyltransferase (HAT) module consisting of GCN5/KAT2A or PCAF/KAT2B, ADA2, ADA3/NGG1, and SGF29 or homologues thereof, a histone deubiquitinase (DUB) module consisting of ATXN7/SGF73, ATXN7L3/SGF11, ENY2/SUS1 and USP22/UBP8 or homologues thereof, and in some taxa a splicing module consisting of SF3B3 and SF3B5 or homologues thereof (not in fungi). In budding yeast also contains Spt8 which distinguishes it from SAGA-like (SLIK) complex (GO:0046695). [PMID:10637607, PMID:17337012, PMID:19056896, PMID:20838651, PMID:33004486]

The SAGA (Spt-Ada-Gcn5-acetyltransferase) complex is a multi-protein complex found in eukaryotes that plays a crucial role in gene transcription. It functions as a histone acetyltransferase (HAT) complex, modifying histones and influencing chromatin structure. The cellular component of the SAGA complex is primarily the nucleus, where it is localized and interacts with DNA and other nuclear proteins. The complex is dynamic and can associate with different regions of the genome depending on the cellular context. The SAGA complex contains several subunits with diverse functions, including:

- **Spt7:** A core subunit that interacts with the TATA-binding protein (TBP) and plays a role in transcription initiation.
- **Spt3:** Another core subunit that interacts with DNA and contributes to the stability of the complex.
- **Ada2:** A subunit involved in recruiting the complex to specific DNA sequences.
- **Gcn5:** The catalytic subunit responsible for histone acetylation.
- **Tra1:** A subunit involved in histone H3 acetylation and regulation of transcription.
- **Ubp8:** A deubiquitinase subunit that removes ubiquitin from histones, impacting chromatin structure.
- **Taf5:** A subunit that interacts with the TATA-binding protein (TBP) and plays a role in transcription initiation.
- **Taf9:** A subunit that interacts with the Spt3 subunit and contributes to the stability of the complex.
- **Taf10:** A subunit that interacts with the Ada2 subunit and helps recruit the complex to specific DNA sequences.
- **Taf12:** A subunit that interacts with the Gcn5 subunit and helps regulate histone acetylation.
- **Taf13:** A subunit that interacts with the Tra1 subunit and helps regulate transcription.

The SAGA complex also contains other subunits that are less well characterized but contribute to its overall function. These subunits include:

- **Spt20:** A subunit that interacts with the Spt7 subunit and contributes to the stability of the complex.
- **Spt21:** A subunit that interacts with the Spt3 subunit and contributes to the stability of the complex.
- **Spt22:** A subunit that interacts with the Ada2 subunit and helps recruit the complex to specific DNA sequences.

In summary, the cellular component of the SAGA complex is the nucleus, where it functions as a HAT complex, modifying histones and influencing chromatin structure. The complex is composed of multiple subunits with diverse functions, including core subunits, catalytic subunits, and regulatory subunits, all working together to regulate gene transcription.'
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Proteins (3)

Compounds (17)